Rheology modifier compositions and methods of use

Abstract

A composition for enhancing fluid viscosity including a mixture of at least one cationic or cationizable polymer and at least one anionic or anionizable (hydrolysable) polymer. The composition has a zeta potential at 25° C. in the range of 0.5 to 100 mV or −0.5 to −100 mV, typically 1 to 60 mV or −1 to −60 mV, or is a precursor convertible at a temperature of 100 to 250° C. to the composition having a zeta potential at 25° C. of 0.5 to 100 mV or −0.5 to −100 mV, typically 1 to 60 mV or −1 to −60 mV. Typically the compositions exhibit salt tolerance and interaction of both polymers at very high temperatures (>300° F.) such that the system exhibits an increase of viscosity at extreme temperatures. The compositions are useful for hydraulic fracturing, enhanced oil recovery, subterranean acidization, personal care as well as home and industrial cleaners.

What is claimed is: 
     
       1. A composition for enhancing viscosity of a fluid comprising a mixture of:
 (A) at least a first polymer having a weight average molecular weight of 35,000 to 10,000,000 selected from at least one member of the group consisting of cationizable polysaccharides with primary amino groups and which are at least partially cationizable to a cationic polymer having a cationic charge density of 0.3 to 2 milliequivalents/gram at a temperature of 100 to 250° C.; 
 (B) at least a second polymer having a weight average molecular weight of 30,000 g/mol to 10,000,000 g/mol selected from the group consisting of: 
 (1) anionic polymers selected from the group consisting of polyacrylic acid, polyacrylamide and acrylate copolymer, the at least one anionic polymer, and having an anionic charge density of 0.1 to 20 milliequivalents/gram, wherein the anionic polymer has functional groups selected from the group consisting of carboxylate, sulfate, sulfonate, phosphate or phosphonate, and 
 (2) hydrolysable polymers selected from the group consisting of polyalkylacrylate, polyacrylamide and copolymers of polyalkylacrylate and polyacrylamide, the hydrolysable polymer having a weight average molecular weight of 30,000 g/mol to 10,000,000 g/mol, and which is at least partially hydrolyzable to an anionic polymer having an anionic charge density of 0.1 to 20 milliequivalents/gram at a temperature of 100 to 250° C., wherein the hydrolysable polymer optionally has functional groups selected from the group consisting of sulfate, sulfonate, phosphate or phosphonate; 
 wherein the composition has a pH of 6 to 12 and a zeta potential at 25° C. in the range of 0.5 to 100 mV or −0.5 to −100 mV. 
 
     
     
       2. A composition for enhancing viscosity of a fluid comprising a mixture of:
 (A) at least a first polymer having a weight average molecular weight of 35,000 to 10,000,000 selected from at least one member of the group consisting of cationizable polymers with at least one member of the group consisting of primary, secondary and tertiary amino groups and which is at least partially cationized or cationizable to a cationic polymer having a cationic charge density of 0.47 to 1.7 milliequivalents/gram at a temperature of 100 to 250° C.; 
 (B) at least a second polymer having a weight average molecular weight of 30,000 g/mol to 10,000,000 g/mol selected from the group consisting of: 
 (1) anionic polymers selected from the group consisting of polyacrylic acid, polyacrylamide and acrylate copolymer, the at least one anionic polymer, and having an anionic charge density of 0.1 to 20 milliequivalents/gram, wherein the anionic polymer has functional groups selected from the group consisting of carboxylate, sulfate, sulfonate, phosphate or phosphonate, and 
 (2) hydrolysable polymers selected from the group consisting of polyalkylacrylate, polyacrylamide and copolymers of polyalkylacrylate and polyacrylamide, the hydrolysable polymer having a weight average molecular weight of 30,000 g/mol to 10,000,000 g/mol, and which is at least partially hydrolyzable to an anionic polymer having an anionic charge density of 0.1 to 20 milliequivalents/gram at a temperature of 100 to 250° C., wherein the hydrolysable polymer optionally has functional groups selected from the group consisting of sulfate, sulfonate, phosphate or phosphonate; 
 wherein the composition has a pH of 6 to 12 and a zeta potential at 25° C. in the range of 0.5 to 100 mV or −0.5 to −100 mV. 
 
     
     
       3. The composition of  claim 2 , wherein the first polymer is selected from at least one member of the group consisting of: polyvinyl amines and polyvinyl amine copolymers such as vinyl amine/vinyl alcohol copolymers or vinyl amine/acrylamide copolymers. 
     
     
       4. A composition for enhancing viscosity of a fluid comprising a mixture of:
 (A) at least a first polymer having a weight average molecular weight of 35,000 to 10,000,000 selected from at least one member of the group consisting of 
 (1) a cationic polysaccharide with quaternized amino functional groups and cationic charge density of 0.3 to 2 milliequivalents/gram, 
 (2) cationizable polysaccharides with primary amino groups and which are at least partially cationizable to a cationic polymer having a cationic charge density of 0.3 to 2 milliequivalents/gram at a temperature of 100 to 250° C., and 
 (3) cationizable polymers with at least one member of the group consisting of primary, secondary and tertiary amino groups and which are at least partially cationizable to a cationic polymer having a cationic charge density of 0.3 to 2 milliequivalents/gram at a temperature of 100 to 250° C.; 
 (B) at least a second polymer having a weight average molecular weight of 30,000 g/mol to 10,000,000 g/mol selected from the group consisting of: 
 anionic polymers comprising a monomeric unit of structure I: 
 
       
         
           
           
               
               
           
         
       
       wherein n ranges from 5 to 50;
 wherein the composition has a zeta potential at 25° C. in the range of 0.5 to 100 mV or −0.5 to −100 mV.